1. Field of the Invention
This invention relates to a light emitting module and the method of the producing the module.
2. Related Prior Art
A typical light emitting module comprises a light emitting semiconductor device such as a laser diode and a package containing the device therein. The package has a rectangle shape, which is called a butterfly package, and provides lead terminals. Electrical signals by which the semiconductor device is driven are lead through lead terminals.
In the conventional module, a sub-assembly in which the light emitting device and some optical members are assembled beforehand is installed into the butterfly package, a bottom member and a side member of the package are rigidly put together. It is necessary to secure an enough space to handle tools for installing the sub-assembly in the package and for electrically connecting between the sub-assembly and lead terminals, which is an obstacle to the small-sized module.
In the conventional package, lead terminals are fixed to the side member of the package; the level of lead terminals is the same as that of the light emitting device. When the module is surface mounted to the motherboard, the lead must be elongated to bend downwardly. The elongated lead coupled with the large package results on the longer path length from the lead terminal, the high frequency signal input thereon, to the light emitting device, which brings the deterioration of the high frequency performance of the module.
The object of the present invention is to provide an advanced optical module and the manufacturing method of the same, which enables a surface mount configuration without causing the inferiority of the high frequency performance.
To realize the object, the module according to the present invention comprises an optical semiconductor device, a package containing the emitting device therein, and lead-terminals. The package comprises a bottom member and a side member. The bottom member may have a device mounting surface, a side member mounting surface surrounding the device mount surface therearound, and a lead forming surface surrounding the side member mounting surface. The device mounting surface mounts the semiconductor device thereon, and the lead terminals contact the lead forming surface thereto.
In the present module, it is enable to bond the side member to the bottom member after mounting the semiconductor device on the device mount surface and electrically connecting the device to peripheral components. Therefore, the side member is not an obstacle in installing the semiconductor device and wiring the device to other devices. Hence, this leads a small sized package.
The configuration of lead terminal that attached to the bottom member of the package shorten the length of the terminal compared with the conventional configuration when the module is surface mounted on a motherboard. Moreover, the size of the module itself is to be small size as mentioned. Therefore, the path from the tip of the terminal, the high frequency signal input therein, to the semiconductor device is shortened, thus prevents the deterioration of the high frequency performance of the module.
It is favorable that the level of the device mounting surface be above that of the lead forming surface, because the alignment between the semiconductor device and an optical fiber, the optical signal transmits therethrough, is facilitated.
It is also favorable that the level of the side member mounting surface is between the lead forming surface and the device mounting surface. The attachment of the side member of the package to the bottom member is simple.
It is favorable to fix the side member to the bottom member after mounting the semiconductor device on the device mounting surface and performing the wire bonding the semiconductor device to the peripheral circuit. This assembling process makes it possible to eliminate the extra space within the package and to shrink the size of the package. The path length from the lead terminal, the high frequency signal input thereto, to the peripheral circuit is shortened, thus prevents the deterioration of the high frequency performance of the module.